Google Voice is a great way to manage phone hell by giving you a single phone number that automatically rings your mobile, home, work and other phones based on your choice of rules and settings (who’s calling, when, etc.). But people are still stuck with their legacy phone numbers, and moving completely away from them is difficult.

I solved the problem by simply porting my mobile number away from AT&T over to Google Voice, a feature that Google says will be launched more broadly eventually.

Others solve the problem via the Google Voice application on various phones. But even then, if someone calls your old mobile number and leaves a message, you have to deal with it separately.

Not any more. Tonight Google is launching a third option, a new feature that allows mobile users to move their voicemail away from their carrier and over to Google Voice. The benefits: your mobile voicemails go into your Google Voice inbox along with other voicemails and text messages, plus you can create custom greetings for callers and your voicemails are all automatically transcribed (sometimes hilariously).

There are a few steps that have to be completed that vary based on the carrier and phone that you use. But if you are really trying to move over to Google Voice, it’s worth it. When it’s all set up, voicemail messages from people who call your mobile number (not your Google Voice number) will be taken over by Google Voice. That makes them much easier to listen to, or read.

And yes, it even works on the iPhone.